Composition of the organic matter of the water, suspended matter, and bottom sediments in Nha Trang Bay in Vietnam in the South China Sea

Dissolved, particulate, and sedimentary organic matter in the Cai River basin (Nha Trang Bay of the South China Sea)

“…However, this assumption requires additional study. At the same time, a considerable contribution into the OM supply (C D + C P ) at the down Cai River, its lowland Dau trib utary, and, especially, in the estuary might be made by human economic activity [5,8].…”

“…The dissolved and particulate organic matter sup plied to the seas by riverine runoff considerably affects the distribution and composition of OM in marine bot tom sediments [7,8]. As a rule, the bulk of riverine C D is presented by humic compounds supplied from the soils of the drainage area.…”

“…The C P supply to the waters of the Cai River estuary resulting from the processes of primary production is minor, as shown by the pronounced decrease of chl a concentration (to 0.8 mg/m 3 at station 6, Table 1). Further from the river mouth, the POC fraction in the particulate matter of the surface water layer of Nha Trang Bay increased to 10-20% and reached its maximum value (25%) in the seaward parts of the aquatic area [8].…”

“…To collect the particulate matter and to deter mine its mass concentration mg/L, the membrane nuclear filters of 47 mm diameter and 0.45 μm pore size were used [3]. Bottom sediments were collected with a sampler; after the lithological description, the samples were dried in a desiccator at 60°C [7,8].…”

“…The South China Sea in the area of Nha Trang Bay is characterized by compli cated hydrodynamic conditions resulting from quite powerful tidal currents and the presence of seasonal upwelling, which affect the sedimentation process. The preceding study has shown that the formation of a composition of organic matter in the waters and bottom sediments of the bay was under the great influence of Cai River runoff [8].…”